Quiz & test questions Grade 12 Careers & CTE

Calderwyn Regional Water: Distribution Operator Exam Review

A grade 12 careers assessment on distribution licensing and operator exam math at a fictional district, with ten items and a fully worked key.

Grade: Grade 12
Subject: Careers & CTE
Material: Quiz & test questions
Time: 45 min
Prep: No prep
Materials: Calculator, Formula sheet with the constants listed in the assessment

Standards

HSN-Q.A.1 Common Core Math

Use units as a way to understand problems and to guide the solution of multi-step problems; choose and interpret units consistently in formulas; choose and interpret the scale and the origin in graphs and data displays.

How this material aligns: Items 3 through 7 carry units through multi-step distribution calculations, converting diameter and depth to gallons and million gallons per day to gallons per minute.

All materials for HSN-Q.A.1 →

HSN-Q.A.3 Common Core Math

Choose a level of accuracy appropriate to limitations on measurement when reporting quantities.

How this material aligns: Items 3 and 5 state the precision of the tank measurement and of the district's pressure gauges, so students must report storage and pressure at a matching level of accuracy.

All materials for HSN-Q.A.3 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-09-23.

Objectives

Students will apply the volume, pressure, flow, and dosage formulas used on distribution operator licensing exams.
Students will explain how license class, scope of practice, and continuing education govern what a distribution operator may do.
Students will report calculated quantities at an accuracy that matches the stated precision of the field instrument.

Vocabulary

Key words: license class, scope of practice, static pressure, chlorine demand, continuing education unit, operator in training

Teacher overview

This 45-minute assessment is worth 32 points and reviews both halves of a distribution operator licensing exam: the rules that define what a licensed operator may legally do, and the arithmetic that a shift operator runs during a normal day. All quantities come from a fictional utility, the Calderwyn Regional Water District, so students work from stated scenario data rather than from any real system. Two items are multiple choice, two are short answer, and six are computation items. One misconception is worth naming before students begin, because it is a common error on operator licensing exams: candidates who remember that one psi equals 2.31 feet of head often multiply feet by 2.31 instead of by 0.433 when converting the other direction, which overstates a tank's pressure by more than a factor of five. Have students write both constants at the top of the page with the direction of each conversion spelled out.

Calderwyn Regional Water: Distribution Operator Exam Review — Grade 12 Careers & CTE

Name: ____________________________ Date: ______________

Assessment

(2 points) The fictional state that licenses Calderwyn issues distribution licenses in four classes. A Class I license covers systems serving up to 1,500 people, Class II covers up to 15,000, Class III covers up to 100,000, and Class IV covers larger systems. Calderwyn serves 34,000 people. An operator who will be the sole licensed staff member on the night shift must hold which class, at minimum?
- A) Class I
- B) Class II
- C) Class III
- D) Class IV
(3 points) In the fictional Calderwyn system, a distribution license authorizes work on mains, storage, pumping, and disinfection within the piping network, while a treatment license authorizes work on the processes inside the plant. State one specific reason a district like this one would pay for a distribution operator to also earn a treatment license.
(4 points) Calderwyn's fictional Hallet Street reservoir is a cylinder with an inside diameter of 60 feet and a water depth of 32 feet. Using volume equals 0.785 times diameter squared times depth, and 7.48 gallons per cubic foot, calculate the volume of water in the tank in gallons. The tank dimensions were measured to the nearest foot, so report your answer to the nearest thousand gallons.
(4 points) The fictional Hallet Street reservoir holds 676,000 gallons when full, and Calderwyn pumps an average of 2.4 million gallons per day into the distribution system. If every pump stopped and the tank simply drained at the average demand rate, how many hours of water would the full tank supply? Report your answer to the nearest tenth of an hour.
(4 points) A service connection in the fictional Calderwyn system sits 145 feet below the overflow elevation of the Hallet Street reservoir. Using 0.433 psi per foot of head, calculate the static pressure at that connection. District pressure gauges read to the nearest tenth of a psi, so report your answer to that precision.
(4 points) Calderwyn's fictional high service pumps deliver 2.4 million gallons per day. Using 694 gallons per minute per million gallons per day, convert that flow to gallons per minute. Round to the nearest whole gallon per minute.
(4 points) The fictional Calderwyn district feeds chlorine at the entry point to the distribution system at a dose of 1.8 mg/L while treating 2.4 million gallons per day. Using pounds per day equals dose times flow in million gallons per day times 8.34, calculate the pounds of chlorine fed per day. Round to the nearest tenth of a pound.
(3 points) An operator in the fictional Calderwyn system doses chlorine at 1.8 mg/L at the entry point and measures a free chlorine residual of 0.6 mg/L at the far end of the Ridgeway Avenue loop. Calculate the chlorine demand between those two points.
(2 points) The fictional state that licenses Calderwyn requires every licensed operator to complete 20 contact hours of approved continuing education in each two-year renewal cycle, and it will not renew a license without them. Which statement best describes what happens to an operator who completes only 12 contact hours in a cycle?
- A) The license renews automatically because the operator is still employed by a licensed utility.
- B) The license lapses at the end of the cycle, and the operator may not sign as the licensed operator in charge until it is restored.
- C) The missing hours are added to the next cycle with no effect on the license.
- D) The utility's license covers the individual operator, so no personal renewal is needed.
(2 points) In the fictional Calderwyn district, an operator in training may perform any field task under the direction of a licensed operator but may not sign a regulatory report or make an unsupervised decision to change disinfection. Name one task from this assessment that only the licensed operator may complete, and state why the district structures the job that way.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

Answer: C) Class III. Calderwyn serves 34,000 people, which falls above the 15,000 ceiling for Class II and within the 100,000 ceiling for Class III, so the sole licensed operator on a shift must hold at least a Class III distribution license.
Answer: Accept any specific, defensible reason for dual licensure.
A strong response names a concrete benefit to the district, for example that a dual-licensed operator can cover a plant shift when the treatment operator is on leave, or can advance to a supervisor role that requires both credentials, or can make disinfection decisions at both the plant and the entry point during a main break.
Answer: 676,000 gallons.
Volume in cubic feet equals 0.785 times 60 squared times 32, which is 0.785 times 3,600 times 32, or 90,432 cubic feet. Gallons equal 90,432 times 7.48, or 676,431 gallons, which rounds to 676,000 gallons at the stated precision.
Answer: 6.8 hours.
676,000 gallons divided by 2,400,000 gallons per day equals 0.2817 day. 0.2817 day times 24 hours per day equals 6.76 hours, which rounds to 6.8 hours.
Answer: 62.8 psi.
145 feet times 0.433 psi per foot equals 62.785 psi, which rounds to 62.8 psi at the gauge's stated resolution.
Answer: 1,666 gpm.
2.4 million gallons per day times 694 gallons per minute per million gallons per day equals 1,665.6 gallons per minute, which rounds to 1,666 gallons per minute.
Answer: 36.0 pounds per day.
1.8 mg/L times 2.4 million gallons per day equals 4.32, and 4.32 times 8.34 equals 36.0288 pounds per day, which rounds to 36.0 pounds per day.
Answer: 1.2 mg/L.
Chlorine demand equals dose minus residual, so 1.8 mg/L minus 0.6 mg/L equals 1.2 mg/L.
Answer: B) The license lapses at the end of the cycle, and the operator may not sign as the licensed operator in charge until it is restored. The stem states that the state will not renew without the full 20 contact hours, and the license belongs to the individual rather than to the employer, which rules out choices A and D.
Answer: Accept any task the stem reserves to a licensed operator, with a reason.
Strong responses name the chlorine dose change implied by item 8, or the signature on the monthly report that carries the pressure reading from item 5, and explain that the state holds a named individual accountable for decisions affecting public health, so the signature has to belong to someone whose training the state has tested.

Differentiation

Support

Give students a printed constants card for the fictional Calderwyn problems that lists 0.785, 7.48 gallons per cubic foot, 0.433 psi per foot, 694 gallons per minute per million gallons per day, and 8.34 pounds per gallon, each with an arrow showing the direction of the conversion. Set up item 3 as far as 0.785 times 3,600 times 32 so that students begin from the multiplication rather than from the formula, and allow partial credit for a correct method with an arithmetic slip.

Extension

Ask students to recalculate items 5 and 7 for a second fictional Calderwyn pressure zone where the service connection sits 92 feet below the overflow and the plant treats 3.1 million gallons per day at the same 1.8 mg/L dose, then write two sentences explaining which of the two zones will be harder to keep above a 20 psi minimum during a fire flow.

ELL supports

Pre-teach license class, scope of practice, residual, demand, and renewal cycle with a one-line definition and a labeled sketch of the fictional Calderwyn reservoir showing overflow elevation, water depth, and the service connection below it. Allow items 2 and 10 to be answered in a sentence frame such as "Only the licensed operator may sign this record because the state holds that person accountable," and permit oral responses recorded by a partner.

Extensions

Have students locate their own state's drinking water operator certification page and compare the license classes and continuing education requirements there with the fictional rules used in items 1 and 9. Most states publish the class thresholds, the exam application, and the renewal cycle at no cost, and a short written comparison gives students an accurate picture of what the credential would actually require where they live.